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atomic clock

noun
1.
an extremely accurate electronic clock regulated by the resonance frequency of atoms or molecules of certain substances, as cesium.
Origin
1935-1940
1935-40
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for atomic clocks

atomic clock

noun
1.
an extremely accurate clock in which an electrical oscillator is controlled by the natural vibrations of an atomic or molecular system such as caesium or ammonia
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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atomic clocks in Science
atomic clock  
An extremely precise clock whose rate is controlled by a periodic process (such as vibration, or the absorption or emission of electromagnetic radiation) that occurs at a steady rate in atoms or molecules. The standard atomic clock is based on the vibrations of cesium atoms and is so accurate that it would gain or lose less than one second in three million years. Atomic clocks are used to help track satellites, run navigation systems, and study movements of the Earth's crust.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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atomic clocks in Culture

atomic clock definition


The most accurate clock available. Time is measured by the movement of electrons in cesium atoms. The standard second is now defined by measurements on an atomic clock.

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Encyclopedia Article for atomic clocks

atomic clock

type of clock that uses certain resonance frequencies of atoms (usually cesium or rubidium) to keep time with extreme accuracy. The electronic components of atomic clocks are regulated by the frequency of the microwave electromagnetic radiation. Only when this radiation is maintained at a highly specific frequency will it induce the quantum transition (energy change) of the cesium or rubidium atoms. In an atomic clock these quantum transitions are observed and maintained in a feedback loop that trims the frequency of the electromagnetic radiation; like the recurrent events in other types of clocks, these waves are then counted.

Learn more about atomic clock with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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10
12
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